Backlight control circuit with under current detection and start-up control

A method for controlling light emission devices, comprising:

• providing a plurality of light emission device paths connected in parallel, each path including at least one light emission device;
• supplying an output voltage to a node where the plurality of light emission device paths are coupled to;
• extracting a voltage signal from each of the plurality of light emission device paths;
• detecting whether each of the plurality of light emission device paths is in an under current status;
• in a start-up period when the light emission devices begin to operate and all of the light emission device paths are in the under current status, supplying the output voltage and neglecting the detection of the under current status;
• leaving the start-up period and entering a normal operation period when there is at least one, but not all, of the light emission device paths which is not in the under current status and before the output voltage reaches an upper limit;
• and
• in the normal operation period, when at least one of the light emission device paths is not in the under current status, selecting the lowest one of the extracted voltages from the plurality of light emission device paths which are not in the under current status, and controlling the output voltage according to the selected lowest voltage.